Hi, If maybe one of you have this problem when changing name you should read this.
My name was BotEuro before i changed it, I changed it to Eurx. In the minecraft profile website it shows i changed it successfully. When i go in the launcher i get confused and i have my old name in buttom right corner. So i launch the game, I can play singleplayer. But i cannot join hypixel and other servers. Affects Version/s - ALL VERSIONS
                                                                Solution
1. Go to the MC Launcher.                                          5. And add the same EMAIL and
2. Go in the Settings. ( Buttom Left )                           PASSWORD for you account.
3. Click Accounts.
4. Add Account.                                                            Your name from OLD will change to NEW.